"It's just hard in this league to be a guy short," Mattingly said. "He felt good enough to [pinch-hit], but with a ground ball, it'll be a double play. At this point, there's not any way he can play the field."
Thames said he felt the injury "on the second or third step" out of the box on a double Friday.
"It's not as bad as I thought it would be," he said.
Thames, signed to handle the bulk of the playing time in left field, had been hampered by a quad strain since Spring Training that ultimately put him on the disabled list from May 3 to June 6. He was 3-for-6 in his last three games and was just starting to get his timing back.
"I'm not too happy right now," he said. "The frustrating part is, I'm finally getting a chance to get in a couple days in a row, and now something else. I just hope it's not bad."
The Dodgers have three outfielders on their 40-man roster at Triple-A Albuquerque from which they can promote a replacement: Jerry Sands, Trayvon Robinson and Jamie Hoffmann. Of the three, only Hoffmann didn't play Saturday, a possible indication that he would be Thames' replacement. Hoffmann is the oldest and most experienced of the trio.
Sands apparently was still struggling with some of the mechanical bad habits that led to his demotion two weeks ago. The latest word on Robinson was that he was making continued progress, but management would prefer to keep him in the Minors through August, if possible.
"Jerry's OK, and Trayvon's been hot lately," said Mattingly. "We feel [Trayvon's] starting to make strides and adjustments. We have to make sure we don't bring guys too fast. We've had to bring guys faster than we've wanted to this year. We've talked about a number of guys [to promote]. I hate to say at this point."
Also at Triple-A is Jay Gibbons, but he no longer is on the 40-man roster.